What is Permafrost?

When you hear the word "permafrost" you probably picture a thick, permanently frozen layer of frost or ice sitting on top of the ground. But permafrost actually refers to the frozen ground itself, regardless of whether there is ice or snow on the ground surface. Look at the two pictures to the right, these people are walking on permafrost in the Alaska tundra, and there is no ice or frost in sight! However, beneath their feet, there are anywhere from 1m to 1000m of frozen ground! That's 3 feet to 3281 feet!

Walking on the permafrost in July near the Toolik Field Station (Alaska)

Dr. Sarah Godsey and Dr. Sarah Evans were recently doing fieldwork in the tundra and explain what permafrost is, in the video below:

What is permafrost frame.mp4

Thaw Vs. Melt

Melting refers to the change in the physical state of matter. For instance - a piece of metal heated to a certain point can change from being a solid to a liquid. Thawing is slightly different in that it is the change from a frozen state to an unfrozen state. Similar to permafrost, when you thaw a steak it does not become a liquid but instead simply loses its "frozen" status and remains solid. 

Where is permafrost found?

Permafrost is found primarily in Arctic regions of the Northern Hemisphere such as Siberia, Alaska, Greenland, and Canada, although there is also some permafrost in the South American Andes, New Zealand, and Antarctica. According to the Natural Resources Defense Council (NRDC), permafrost currently covers around 9 million square miles of the Northern Hemisphere (almost the size of the US, Canada, and China combined!). 

This map created by GRID-Arendal/Nunataryuk shows the extent of permafrost around the globe in the land and seafloor. (Click on the image to view it larger) 

Here's a neat thing you can make- a 3D foldable version of this map!